NASA-Inspired Insulation: Made with Polartec Powerstretch fabric to trap air and retain heat better than water. Lightweight & Low Bulk: Delivers warmth without compromising mobility or adding unnecessary buoyancy. Fast-Wicking & Quick-Drying: Keeps skin drier and more comfortable during and after dives. Reliable Wet Performance: Maintains insulation properties even when wet, ensuring dependable thermal protection. Durable & Easy Care: Hardwearing, machine washable, and compatible with eco-friendly Sub30 Technical Garment Wash. Engineered for serious divers, the Fourth Element Men's Xerotherm Long Sleeve Top is the ultimate baselayer for drysuit diving. Crafted with advanced Polartec Powerstretch fabric originally developed for NASA, it traps a thin layer of insulating air against the skin—far superior to water—offering exceptional warmth and comfort. Whether worn alone under a neoprene drysuit or layered beneath another undersuit, the Xerotherm delivers outstanding thermal performance without adding bulk or buoyancy. Fast-wicking, durable, and machine washable, it's designed to perform even when wet—keeping you dry, warm, and ready for your next dive.